Pillow plate for fermentation and thermal control in wineries and breweries
Pillow plate heat exchangers in breweries and wineries: fermentation cooling and tank temperature control | BOIXAC Technical blog · Food industry › Breweries and wineries Pillow plate heat exchangers in breweries and wineries: fermentation cooling and tank thermal control Why dimple plate technology outperforms conventional jackets for fermentation tank cooling: heat transfer coefficient analysis, CIP cleaning and design criteria for beer and wine production. BOIXAC · Technical OfficeUpdated: 2026Reading: ~11 min Note on the scope of this article This article is of a general technical and informational nature. Heat transfer coefficient values, temperature ranges and design criteria given are indicative; the definitive sizing of a pillow plate heat exchanger for a specific application requires analysis of the actual process conditions by qualified engineers. BOIXAC assumes no liability for decisions taken on the basis of this article. Temperature control during fermentation is one of the technical parameters with the greatest influence on the organoleptic profile of the final product in breweries and wineries. The difference between a fermentation proceeding at 12 °C and one that peaks at 18 °C may be the difference between a clean product and one with undesirable ester and fusel alcohol profiles. Pillow plate technology — also known as dimple plate — has progressively replaced half-pipe jackets and conventional annular jackets on next-generation stainless steel fermentation vessels, thanks to thermal, hygienic and constructional advantages that become especially evident in tank volumes exceeding 5,000 litres. 1. Operating principle of the pillow plate (dimple plate) A pillow plate is a heat exchanger formed by two stainless steel sheets joined at their perimeter and by a regular matrix of resistance spot welds, creating an internal labyrinthine cavity with a very narrow cross-section. When a refrigerant fluid (typically aqueous glycol) circulates through this cavity, the dimple geometry induces local turbulent flow — even at low volumetric flow rates — maximising the internal convection coefficient. The outer sheet of the pillow plate is welded directly to the surface of the fermentation vessel, so that the tank wall simultaneously serves as the load-bearing structure and the heat transfer surface. The embossed geometry of the dimples distributes the refrigerant pressure uniformly across the entire plate surface, allowing operation at relatively high internal pressures (up to 10–15 bar depending on design and sheet thickness) with minimal material thickness. 2. Technical comparison: pillow plate vs. conventional jackets Parameter Pillow plate (dimple plate) Half-pipe jacket Conventional annular jacket Internal convective coefficient (hi) High: dimple geometry induces local turbulence. Typical values: 3,000–8,000 W/m²·K. Moderate-high: tubular flow. 2,000–5,000 W/m²·K. Low-moderate: wide annular flow, often laminar. 500–2,000 W/m²·K. Cooling distribution across tank surface Excellent: continuous, uniform coverage of all covered surface. Good along the pipe length; zones between pipes lack direct contact. Variable: risk of dead zones in large-section annular circuit. Refrigerant fluid volume in circuit Very low: narrow flow passage (typically 3–6 mm). Reduced glycol volume in circuit. Moderate. High: large annular cross-section. Thermal response time Very fast: low fluid volume, reduced thermal inertia. Rapid control system response. Fast-moderate. Slow: large fluid volume, high thermal inertia. Slow response to setpoint changes. Cleanability — product side Excellent: smooth external surface in contact with product, suitable for CIP cleaning. Good. Good. 3. Specific applications in breweries and wineries 3.1. Fermentation vessel cooling in brewing In bottom-fermentation (lager) beer production, temperature control is especially critical because the yeast working window (typically 8–14 °C for standard lager strains) is narrow and the heat generated by alcoholic fermentation is significant: approximately 2.3 kJ are released per gram of fermented sugar. In a 50-hl fermenter with 12 °P wort, the cooling duty required at peak fermentation activity can be between 3 and 8 kW depending on the fermentation rate. Pillow plates welded to the cylindrical tank wall (and, in some designs, to the cone) allow this heat extraction to be distributed homogeneously, avoiding radial temperature gradients that could create localised sub-cooling zones where yeast activity is inhibited or premature precipitation occurs. The fast response of the system — due to the low refrigerant circuit volume — facilitates the use of PID control systems that maintain temperature setpoints within ±0.5 °C, difficult to achieve with high-inertia conventional jackets. 3.2. Must temperature control in wine fermentation In white and rosé winemaking, fermentation temperature control (typically between 12 and 18 °C) is critical for preserving volatile varietal aromas that are lost through volatilisation if temperatures are exceeded. Pillow plates on AISI 304 or 316L stainless steel tanks allow low fermentation temperatures to be reached and maintained with modest refrigeration systems. The ability to reach temperatures close to 0 °C uniformly and in a controlled manner — the so-called cold tartrate stabilisation — is an application that highlights the thermal performance of pillow plate technology over less efficient alternatives. 3.3. Craft breweries and microbreweries In craft breweries with smaller fermenters (100–2,000 litres), pillow plate technology offers additional advantages due to its compatibility with relatively small glycol systems and the ease of integration on cylindroconical stainless steel tanks. The typical configuration consists of one or two independent pillow plate zones (cylindrical and conical sections) connected to a glycol circuit with independent zone control valves, allowing programmable temperature profiles throughout fermentation. 4. Pillow plate sizing criteria for fermentation vessels Peak fermentation thermal duty (Qmax): estimated from fermentation rate, wort concentration (°P or °Brix) and tank volume. In beer production, indicative reference values range from 50 to 150 W per hl of fermenter capacity at peak activity, depending on the recipe and yeast used. Available temperature differential (ΔT): difference between fermenting product temperature and refrigerant inlet temperature to the plate. Minimum refrigerant temperature: in aqueous glycol circuits, glycol temperatures of -2 to -5 °C are generally sufficient for most standard fermentation applications; lower temperatures are used for tartrate stabilisation. Tank surface coverage: the proportion of the total tank surface covered with pillow plate (typically 40–70 % of the lateral surface) must be sufficient to ensure cooling uniformity and avoid vertical temperature gradients in the product. Refrigerant circuit working pressure: pillow plate … Read more